function sp = sim_par

sp.N = 2^5;    % number of wavenumbers
sp.Nz = 50;    % number of grid points in z direction

sp.dx = 2 * pi / sp.N;     % x spacing
sp.dz = 1 / (sp.Nz - 1);  % z spacing


sp.k_min = 1;  % minimum k to resolve (sets length of domain)

% compute wavenumbers, x grid, z grid
sp.k = sp.k_min * [0:sp.N/2 - 1 0 -sp.N/2+1:-1];
sp.x = sp.dx * (1:sp.N) / sp.k_min;
sp.z = linspace(0, 1, sp.Nz);

sp.K = repmat(sp.k, sp.Nz, 1);
sp.K2 = sp.K.^2;